Micrometer-gage



(No Model.)

P. CLIFFORD &'J. GOUP'AL.

MIGROMETER GAGE.

No. 335,110; Patented Peb.- 2, 1886.

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UNITED STATES PATENT OFFICE.

PATRICK CLIFFORD AND JOSEPH COUPAL, OF WOLLASTON HEIGHTS, MASSACHUSETTS.

MlCROMETER-GAGE.

SPECIFICATION forming part of Letters Patent No. 335,110, dated February 2, 1.886.

Application filed December 4, 1884. Serial No. 149,531. (No model) To all whom it may concern:

Be it known that we, PATRICK CLIFFORD and Josnrrr COUPAL, citizens of the United States, residing at Wollaston Heights, in the county of Norfolk and State of Massachusetts, have invented a new and useful Improvement in Micrometers, and in the Method of Manufacturing them, of which the following is a specification.

Our invention relates to improvements in micrometers which are used by machinists and others who have to measure thicknesses with great accuracy. It is provided with two dead flat surfaces, between which the article to be measured is placed. The distance be-' tween these two surfaces can be increased or diminished with such accuracy that the exact thickness of the intervening object can be determined. We attain this result by the mechanism illustrated in the accompanying drawings, in which- Figure 1 is an elevation of the entire instrument. Fig. 2 is avertical section of same. Fig. 3 is a vertical section of sleeve 0 and upper part of A A, showing the right-handed and the left-handed screw-threads in operation, enlarged; Fig. 4, a plan of same.

Into the sleeve 0 is driven a cylinder, G, having on its lower and outer end a lefthanded screw, H, in Fig. 2, extending upward about three-quarters of an inch. On the inside of the cylinder G, Fig. 2, there is a right-handed screw-thread, J, at the same end and extending upward about same distance as the screw H on the outside. On the upper end of bar F, which is secured to the lower jaw, B, of the instrument, is a right handed screw-thread,which fits into the screwthread J Fig. 2. At the upper end of and inside of the central part of A Ais a left-handed screwthread,which fits the screw H, and on which it runs up and down.

When set for measuring, the right-handed screw K, which raises the lower jaw, B, turns simultaneously with the left-handed screw H, which moves the upper jaw, A, downward, or vice versa. Thus a double motion is secured, and although both screws are forty threads to the inch, the double action of one working inside the other closes or opens the jaws in half the time, or at therate of a screw of twenty threads to the inch. Of course, any number of threads to the inch may be used with the same results, though in the present case we prefer to use forty. By using this double motion we get another advantage-the instrument need not be so long, for it only lengthens half an inch in opening the space between D and L one inch.

D and L are two perfectly fiat surfaces, between which the object to be measured is placed. At the opposite side to D and L is a graduated guide-bar, E, which is secured to the jaw or frame B, and the jaw or frame A A slides up and down on it. This bar E may be round, flat, or any shape on which figures can be stamped or cut in. The bar E keeps the advancingor retiring jaw A A steady and the surfaces D and L opposite each other, and is divided by marks one-twentieth of an inch apart. The lower edge of sleeve 0 is also equally divided into fifty spaces by marks. It will now be seen that when the sleeve 0 is turned round one space the jaws D and L are closed or opened one-thousandth part of an inch. One revolution of sleeve 0 closes or opens it one twentieth of an inch, or one space on the guide-bar E. The two surfaces D and L are the ends of screws tightly fitting into A A and B, for the purpose of adjusting them. We prefer tohave them made in this manner, though in some cases,where there is not much room, long thin jaws, as M M, would have to be used.

We do not confine ourselves to any particular shape. From the lower end of the screw H upward for about three-fourths of an inch we out two slots about one-fourth of an inch apart. This makes a tongue, 0, which we press inward. It then acts as a spring, andpresses on the screw K, and by this constant pressure takes up all backlash or looseness, which might otherwise occur by wearing out.

Heretofore micrometers have been, from their shape and arrangement, made from forgings or castings; but the most important part indicating-gages for the purpose of measuring ID of our inventionA A and Bare planed or thicknesses, substantially as described, for the milled out from a bar of steel. purpose specified.

Having described our invention, what We claim, and desire to secure by Letters Patent of the United States, is

The combination of a right-handed and left- Witnesses: handed screW,When operating simultaneously CHAS. STORER, inside each other, with a micrometer having JOHN W. STORER.

PATRICK CLIFFORD. JOSEPH COUPAL. 

